1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  *	uvc_queue.c  --  USB Video Class driver - Buffers management
4  *
5  *	Copyright (C) 2005-2010
6  *	    Laurent Pinchart (laurent.pinchart@ideasonboard.com)
7  */
8 
9 #include <linux/atomic.h>
10 #include <linux/kernel.h>
11 #include <linux/mm.h>
12 #include <linux/list.h>
13 #include <linux/module.h>
14 #include <linux/usb.h>
15 #include <linux/videodev2.h>
16 #include <linux/vmalloc.h>
17 #include <linux/wait.h>
18 
19 #include <media/v4l2-common.h>
20 #include <media/videobuf2-vmalloc.h>
21 
22 #include "uvc.h"
23 
24 /* ------------------------------------------------------------------------
25  * Video buffers queue management.
26  *
27  * Video queues is initialized by uvcg_queue_init(). The function performs
28  * basic initialization of the uvc_video_queue struct and never fails.
29  *
30  * Video buffers are managed by videobuf2. The driver uses a mutex to protect
31  * the videobuf2 queue operations by serializing calls to videobuf2 and a
32  * spinlock to protect the IRQ queue that holds the buffers to be processed by
33  * the driver.
34  */
35 
36 /* -----------------------------------------------------------------------------
37  * videobuf2 queue operations
38  */
39 
40 static int uvc_queue_setup(struct vb2_queue *vq,
41 			   unsigned int *nbuffers, unsigned int *nplanes,
42 			   unsigned int sizes[], struct device *alloc_devs[])
43 {
44 	struct uvc_video_queue *queue = vb2_get_drv_priv(vq);
45 	struct uvc_video *video = container_of(queue, struct uvc_video, queue);
46 
47 	if (*nbuffers > UVC_MAX_VIDEO_BUFFERS)
48 		*nbuffers = UVC_MAX_VIDEO_BUFFERS;
49 
50 	*nplanes = 1;
51 
52 	sizes[0] = video->imagesize;
53 
54 	return 0;
55 }
56 
57 static int uvc_buffer_prepare(struct vb2_buffer *vb)
58 {
59 	struct uvc_video_queue *queue = vb2_get_drv_priv(vb->vb2_queue);
60 	struct vb2_v4l2_buffer *vbuf = to_vb2_v4l2_buffer(vb);
61 	struct uvc_buffer *buf = container_of(vbuf, struct uvc_buffer, buf);
62 
63 	if (vb->type == V4L2_BUF_TYPE_VIDEO_OUTPUT &&
64 	    vb2_get_plane_payload(vb, 0) > vb2_plane_size(vb, 0)) {
65 		uvc_trace(UVC_TRACE_CAPTURE, "[E] Bytes used out of bounds.\n");
66 		return -EINVAL;
67 	}
68 
69 	if (unlikely(queue->flags & UVC_QUEUE_DISCONNECTED))
70 		return -ENODEV;
71 
72 	buf->state = UVC_BUF_STATE_QUEUED;
73 	buf->mem = vb2_plane_vaddr(vb, 0);
74 	buf->length = vb2_plane_size(vb, 0);
75 	if (vb->type == V4L2_BUF_TYPE_VIDEO_CAPTURE)
76 		buf->bytesused = 0;
77 	else
78 		buf->bytesused = vb2_get_plane_payload(vb, 0);
79 
80 	return 0;
81 }
82 
83 static void uvc_buffer_queue(struct vb2_buffer *vb)
84 {
85 	struct uvc_video_queue *queue = vb2_get_drv_priv(vb->vb2_queue);
86 	struct vb2_v4l2_buffer *vbuf = to_vb2_v4l2_buffer(vb);
87 	struct uvc_buffer *buf = container_of(vbuf, struct uvc_buffer, buf);
88 	unsigned long flags;
89 
90 	spin_lock_irqsave(&queue->irqlock, flags);
91 
92 	if (likely(!(queue->flags & UVC_QUEUE_DISCONNECTED))) {
93 		list_add_tail(&buf->queue, &queue->irqqueue);
94 	} else {
95 		/* If the device is disconnected return the buffer to userspace
96 		 * directly. The next QBUF call will fail with -ENODEV.
97 		 */
98 		buf->state = UVC_BUF_STATE_ERROR;
99 		vb2_buffer_done(vb, VB2_BUF_STATE_ERROR);
100 	}
101 
102 	spin_unlock_irqrestore(&queue->irqlock, flags);
103 }
104 
105 static const struct vb2_ops uvc_queue_qops = {
106 	.queue_setup = uvc_queue_setup,
107 	.buf_prepare = uvc_buffer_prepare,
108 	.buf_queue = uvc_buffer_queue,
109 	.wait_prepare = vb2_ops_wait_prepare,
110 	.wait_finish = vb2_ops_wait_finish,
111 };
112 
113 int uvcg_queue_init(struct uvc_video_queue *queue, enum v4l2_buf_type type,
114 		    struct mutex *lock)
115 {
116 	int ret;
117 
118 	queue->queue.type = type;
119 	queue->queue.io_modes = VB2_MMAP | VB2_USERPTR | VB2_DMABUF;
120 	queue->queue.drv_priv = queue;
121 	queue->queue.buf_struct_size = sizeof(struct uvc_buffer);
122 	queue->queue.ops = &uvc_queue_qops;
123 	queue->queue.lock = lock;
124 	queue->queue.mem_ops = &vb2_vmalloc_memops;
125 	queue->queue.timestamp_flags = V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC
126 				     | V4L2_BUF_FLAG_TSTAMP_SRC_EOF;
127 	ret = vb2_queue_init(&queue->queue);
128 	if (ret)
129 		return ret;
130 
131 	spin_lock_init(&queue->irqlock);
132 	INIT_LIST_HEAD(&queue->irqqueue);
133 	queue->flags = 0;
134 
135 	return 0;
136 }
137 
138 /*
139  * Free the video buffers.
140  */
141 void uvcg_free_buffers(struct uvc_video_queue *queue)
142 {
143 	vb2_queue_release(&queue->queue);
144 }
145 
146 /*
147  * Allocate the video buffers.
148  */
149 int uvcg_alloc_buffers(struct uvc_video_queue *queue,
150 			      struct v4l2_requestbuffers *rb)
151 {
152 	int ret;
153 
154 	ret = vb2_reqbufs(&queue->queue, rb);
155 
156 	return ret ? ret : rb->count;
157 }
158 
159 int uvcg_query_buffer(struct uvc_video_queue *queue, struct v4l2_buffer *buf)
160 {
161 	return vb2_querybuf(&queue->queue, buf);
162 }
163 
164 int uvcg_queue_buffer(struct uvc_video_queue *queue, struct v4l2_buffer *buf)
165 {
166 	unsigned long flags;
167 	int ret;
168 
169 	ret = vb2_qbuf(&queue->queue, NULL, buf);
170 	if (ret < 0)
171 		return ret;
172 
173 	spin_lock_irqsave(&queue->irqlock, flags);
174 	ret = (queue->flags & UVC_QUEUE_PAUSED) != 0;
175 	queue->flags &= ~UVC_QUEUE_PAUSED;
176 	spin_unlock_irqrestore(&queue->irqlock, flags);
177 	return ret;
178 }
179 
180 /*
181  * Dequeue a video buffer. If nonblocking is false, block until a buffer is
182  * available.
183  */
184 int uvcg_dequeue_buffer(struct uvc_video_queue *queue, struct v4l2_buffer *buf,
185 			int nonblocking)
186 {
187 	return vb2_dqbuf(&queue->queue, buf, nonblocking);
188 }
189 
190 /*
191  * Poll the video queue.
192  *
193  * This function implements video queue polling and is intended to be used by
194  * the device poll handler.
195  */
196 __poll_t uvcg_queue_poll(struct uvc_video_queue *queue, struct file *file,
197 			     poll_table *wait)
198 {
199 	return vb2_poll(&queue->queue, file, wait);
200 }
201 
202 int uvcg_queue_mmap(struct uvc_video_queue *queue, struct vm_area_struct *vma)
203 {
204 	return vb2_mmap(&queue->queue, vma);
205 }
206 
207 #ifndef CONFIG_MMU
208 /*
209  * Get unmapped area.
210  *
211  * NO-MMU arch need this function to make mmap() work correctly.
212  */
213 unsigned long uvcg_queue_get_unmapped_area(struct uvc_video_queue *queue,
214 					   unsigned long pgoff)
215 {
216 	return vb2_get_unmapped_area(&queue->queue, 0, 0, pgoff, 0);
217 }
218 #endif
219 
220 /*
221  * Cancel the video buffers queue.
222  *
223  * Cancelling the queue marks all buffers on the irq queue as erroneous,
224  * wakes them up and removes them from the queue.
225  *
226  * If the disconnect parameter is set, further calls to uvc_queue_buffer will
227  * fail with -ENODEV.
228  *
229  * This function acquires the irq spinlock and can be called from interrupt
230  * context.
231  */
232 void uvcg_queue_cancel(struct uvc_video_queue *queue, int disconnect)
233 {
234 	struct uvc_buffer *buf;
235 	unsigned long flags;
236 
237 	spin_lock_irqsave(&queue->irqlock, flags);
238 	while (!list_empty(&queue->irqqueue)) {
239 		buf = list_first_entry(&queue->irqqueue, struct uvc_buffer,
240 				       queue);
241 		list_del(&buf->queue);
242 		buf->state = UVC_BUF_STATE_ERROR;
243 		vb2_buffer_done(&buf->buf.vb2_buf, VB2_BUF_STATE_ERROR);
244 	}
245 	/* This must be protected by the irqlock spinlock to avoid race
246 	 * conditions between uvc_queue_buffer and the disconnection event that
247 	 * could result in an interruptible wait in uvc_dequeue_buffer. Do not
248 	 * blindly replace this logic by checking for the UVC_DEV_DISCONNECTED
249 	 * state outside the queue code.
250 	 */
251 	if (disconnect)
252 		queue->flags |= UVC_QUEUE_DISCONNECTED;
253 	spin_unlock_irqrestore(&queue->irqlock, flags);
254 }
255 
256 /*
257  * Enable or disable the video buffers queue.
258  *
259  * The queue must be enabled before starting video acquisition and must be
260  * disabled after stopping it. This ensures that the video buffers queue
261  * state can be properly initialized before buffers are accessed from the
262  * interrupt handler.
263  *
264  * Enabling the video queue initializes parameters (such as sequence number,
265  * sync pattern, ...). If the queue is already enabled, return -EBUSY.
266  *
267  * Disabling the video queue cancels the queue and removes all buffers from
268  * the main queue.
269  *
270  * This function can't be called from interrupt context. Use
271  * uvcg_queue_cancel() instead.
272  */
273 int uvcg_queue_enable(struct uvc_video_queue *queue, int enable)
274 {
275 	unsigned long flags;
276 	int ret = 0;
277 
278 	if (enable) {
279 		ret = vb2_streamon(&queue->queue, queue->queue.type);
280 		if (ret < 0)
281 			return ret;
282 
283 		queue->sequence = 0;
284 		queue->buf_used = 0;
285 	} else {
286 		ret = vb2_streamoff(&queue->queue, queue->queue.type);
287 		if (ret < 0)
288 			return ret;
289 
290 		spin_lock_irqsave(&queue->irqlock, flags);
291 		INIT_LIST_HEAD(&queue->irqqueue);
292 
293 		/*
294 		 * FIXME: We need to clear the DISCONNECTED flag to ensure that
295 		 * applications will be able to queue buffers for the next
296 		 * streaming run. However, clearing it here doesn't guarantee
297 		 * that the device will be reconnected in the meantime.
298 		 */
299 		queue->flags &= ~UVC_QUEUE_DISCONNECTED;
300 		spin_unlock_irqrestore(&queue->irqlock, flags);
301 	}
302 
303 	return ret;
304 }
305 
306 /* called with &queue_irqlock held.. */
307 struct uvc_buffer *uvcg_queue_next_buffer(struct uvc_video_queue *queue,
308 					  struct uvc_buffer *buf)
309 {
310 	struct uvc_buffer *nextbuf;
311 
312 	if ((queue->flags & UVC_QUEUE_DROP_INCOMPLETE) &&
313 	     buf->length != buf->bytesused) {
314 		buf->state = UVC_BUF_STATE_QUEUED;
315 		vb2_set_plane_payload(&buf->buf.vb2_buf, 0, 0);
316 		return buf;
317 	}
318 
319 	list_del(&buf->queue);
320 	if (!list_empty(&queue->irqqueue))
321 		nextbuf = list_first_entry(&queue->irqqueue, struct uvc_buffer,
322 					   queue);
323 	else
324 		nextbuf = NULL;
325 
326 	buf->buf.field = V4L2_FIELD_NONE;
327 	buf->buf.sequence = queue->sequence++;
328 	buf->buf.vb2_buf.timestamp = ktime_get_ns();
329 
330 	vb2_set_plane_payload(&buf->buf.vb2_buf, 0, buf->bytesused);
331 	vb2_buffer_done(&buf->buf.vb2_buf, VB2_BUF_STATE_DONE);
332 
333 	return nextbuf;
334 }
335 
336 struct uvc_buffer *uvcg_queue_head(struct uvc_video_queue *queue)
337 {
338 	struct uvc_buffer *buf = NULL;
339 
340 	if (!list_empty(&queue->irqqueue))
341 		buf = list_first_entry(&queue->irqqueue, struct uvc_buffer,
342 				       queue);
343 	else
344 		queue->flags |= UVC_QUEUE_PAUSED;
345 
346 	return buf;
347 }
348 
349